Safety control apparatus



May 23, 1933 F. D. AUSTIN SAFETY CONTROL APPARATUS Original Fil'ed Aug. 21, 1929 2 Sheets-Sheet 1 FlELl.

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May 23, 1933. us 1,910,944

SAFETY CONTROL APPARATUS Original Filed Aug. 21, 1929 2 SheetsSheg t 2 FREDERICKDAUSTIN) Patented May 23, 1933 UNITED STATES PATENT, OFFICE rREDERIcE D. AUSTIN, or [PORT CHESTER, NEW YORK, nssrenoR To AMERICAN SAFETY BOILER CONTROL CORPORATION, or PORT CHESTER, NEW YORK, A 00R- PORATION OF NEW YOIRIK SAFETY CONTROL APPARATUS Application filed August 21, 1929, Serial No. 387,422. Renewed October 12, 1932.

This invention relates to improvements in safety control apparatus for boilers, and more particularly to the type covered by my co-pending application, Serial No. 363,- 623, filed May 16, 1929, and has as its essential object the simplification and increase in dependability and effectiveness of control maintenance.

With these and further objects in view as will in part hereinafter become apparent and in part be stated, the invention comprises a thermally responsive circuitcloser for the power circuit of an automatic fuel feed, and means for enabling the circuit closer to be subjected to internal boiler temperature while safeguarded from other 1nternal boiler influences.

In greater detail, the invention also includes in a structure such as just stated meansfor preventing shortcircuiting of the power current incident to response of the circuit closer to excessive temperature.

The invention also comprises other novel details, combinations, and constructions of parts directed to the increase in the practicability and efliciency of the device to effectively guard against excessive temperatures within the-boiler, such as may arise from too low a drop of the liquid level therein.

In the accompanying drawings,

Figure 1 is a partially diagrammatic showing and partially sectional elevation of an embodiment of the present invention, the parts being illustrated as inoperative relation to a boiler. I

Figure 2 is a longitudinal, central section through an apparatus embodying the features of the present invention, parts being seen in elevation and the parts being shown on an enlarged scale, and the section being taken on the plane indicated by line 22 of Figure 3.

Figure 3 is a transverse section taken on the plane indicated by line 3-3 of Figure 2, and looking in the direction indicated by the arrow.

Figure 4 is a transverse section taken on the plane indicated by line 44 of Figure 2, and looking in the direction indicated by the arrow. I

Figure 5 is a side elevation of the contact closing plug detached.

Figures 6 and 7 are plan views of the halves of the insulator bar with the circuit corporating the principles of my said 00- pending application while materially improving and refining'the mechanical details in a manner to produce a practical,

commercial article of highest dependable efiiciency.

Referring to the drawings by numerals, 1 indicates any form of boiler or container for water or other liquid to be heated, while 2 indicates the blower or other operative parts for the automatic fuel feed for the furnace portion of boiler 1, said parts being actuated by an electric motor indicated diagrammatically at 3. Motor 3 is energized by current received through legs 4 and 5 leading from power lines 6, 6. Since these parts are shown only diagrammatically, no attempt has been made to illustrate the master control switch or other usually employed control apparatus, but it will be understood that all such devices will be utilized according to the preference of the user.

It is, of course, well known that through unforeseen conditions emergencies arise in the use of water heaters or boilers resulting in the dropping of the liquid level below the safety elevation and disastrous results are liable to and do follow if the heat is not reduced or discontinued. The present invention provides means absolutely assuring discontimiance of the fuel supply immediately upon the liquid level dropping too low or any other thing occurring within the boiler causing a dangerously high temperature to be reached.

In the carrying out of the invention, a shell or tubular housing 7 is provided and preferably formed of non-corrosive material. The shell 7 has its inner end closed at 8, and an outer portion of the shell is thickened and provided with threads or other appropriate anchorage means 9 adapted to secure the shell 7 in the desired relation to the boiler 1. hen the securing means 9 is a thread, as is preferable, the wall of the boiler 1 will be apertured and tapped with an appropriate thread to receive the thread 9, and, in fact, the thread 9 is standard to cooperate with threaded openings already present in practically all boilers. Outward of the thread 9, the housing 7 is extended and enlarged to form a nut-like head 10. Of course, head 10 may be otherwise shaped but should have such a contour as to facilitate receiving a tool for threading the shell 7 to and from its operative relation in boiler 1. The bore of shell 7 is preferably somewhat enlarged within the head 10, and is provided with a thread or other appropriate anchorage means 11 to receive a threaded portion 12 of an insulating bar 13. The bar 13 is provided outward of the threaded portion 12 with an enlargement-or cylindrical portion 14, and inward of the threaded portion 12, the bar 13 is reduced and extended throughout the greater portion of the length of the shell 7 but out of contact with the shell.

The bar 13 is formed of any appropriate insulating material, but is preferably formed of bakelite or like substance, and while capable of being constructed in any of various ways is preferably cast in halves, as indicated at 13', 13 in Figures 6 and 7. Each of the said halves is formed throughout the reduced portion with grooves 15, 15, each of the grooves 15 of one half being located to register with the corresponding grooves 15 of the other half, so as to provide spaced passageways throughout the length of the bar 13 when the parts are assembled. The outer terminus of each groove 15 is formed into an enlarged recess 16, the two recesses of one half 13 registering with those of the other half when the parts are assembled to provide slot-like sockets. Arranged within the thus-produced passages 15 are electrodes or terminals 17, 17, each having at its outer end a flattened prong 18 bent to provide spring-like action and insure effective and resilient contact with a contact bar inserted in the respective slot-like sockets 16, as hereinafter pointed out. The

parts are assembled by placing the electrodes 17 in a pair of grooves 15 and placing the other half upon the one carrying the electrodes. Vhen bakelite is employed as the material from which the insulating bar 13 is formed, bakelite cement is applied to the parts before assemblage, and the parts are dried under pressure aftcassemblage in a manner to produce a practically homogeneous, integral structure. Obvious y, the insulating bar 13 may be otherwise produced, as by being formed of gutta percha or other appropriate material in which the necessary passageways for the electrodes are formed in any well known manner, but the bakelite construction is known by me to be effective and thoroughly commercially pram ticable.

The conductors or electrodes 17, as clearly seen both in Figure 7 and in Figure 2, are arranged to project at 19, 19 beyond the inner end of insulating bar 13 and to ceive therebetween an electrical contactpiece or fuse element 20 which of ample conductivity to insure against any possible fusing by the electric current. The fuse 2 is not electrically responsive in the sense of being liable to fuse on overload, but is formed of material designed to be thermally responsive and to fuse when the temperature rises above the predetermined point. For example, if one arbitrarily assumes that 185 F. is the maximum temperature to which a hot water heating system should be raised with safety, the fuse element 20 for such a boiler will. be formed of a compound or metal alloy highly electrically conductive but adapted and destined to melt down when the temperature of the fuse element reaches 185 F. Again, if with vapor or steam heating systems. the maximum temperature for safety is fixed at 220 E, then for such a boiler the compound or alloy of which the fuse 20 is formed is adjusted and proportioned to melt down when the fuse is raised to a temperature of 220 E, and the same thing proportionally can be said for any other established temperature, as, for example, where 235 F. is considered safe for a high pressure or super heated steam boiler.

lVhatever may be the constituents of the fuse 20 and its corresponding melting point. the size and shape of the fuse element will be the same or substantially the same, and. in fact, in practice I have found it desirable to utilize other means than the size and natural appearance of the several fuse elements of differentheat resistances to indicate the capacity of each. Each element. as clearly seen in Figure a, is preferably formed with a centrally enlarged portion and bifurcated terminals with a wasp-waist or restricted portion between the centrally enlarged portion and each of said terminals. Each bifurcated end portion'is preferably shaped to have the furcations partly enclose the respective projecting terminal 19 so that when a fuse is applied between the terminals and slid onto the same until'it contacts with the inner end of the bar 13, the fuse cannot be removed edgewise except upon fusing and may be removed only laterally. However, on fusing, the restricted or wasp-waist portions of the fuse give way first and the enlarged central portion, by virtue of its weight, tends by gravity to pull the whole structure downward clear of the terminals 19 so as to make a clear-cut break inithe circuit, which includes the terminals 19.

To insure an effective electrical contact between the terminals 19 and the fuse 20, a wedging cover block 21 is preferably provided and may be in the form of a disc, as seen in Figure 4, but may be otherwise shaped as desired. The block 21 is provided with apertures 22, 22 spaced apart from cenfor to center a very slight distance less than the centering of the terminals 19, and the apertures 22 are of approximately the same diameter as the terminals 19, being only sufficiently larger to slide readily on said terminals. is such that the free'ends of terminals 19 can be sprung very slightly into said apertures, and the block 21 can then be slid toward the fuse 20, after the latter has been positioned. This movement of wedging block 21 draws or wedges the terminals 19 toward each other, and thus causes them to impinge more closely against the bifurcated ends of the fuse 20.

Since it is possible for fused material. from the fuse element 20 to accumulate or to become deposited in a manner to close the circuit between one of the terminals 19 and the shell 7, it is desirable to provide against such possible contingency. To this end, a cap 23 of insulating material is preferably detachably fitted over the inner terminal portion of the insulating bar 13, and located to prevent short-circuiting from such deposit or from contact of one of the terminals with the wall of shell 7. The parts are, of course, proportioned to accommodate the cap 23 within the shell 7 while providing ample space within cap 23 to accommodate a melted-down fuse 20 without danger of short-circuiting.

A standard, commercial, contact-making plug 24 having the usual contact prongs 25 is employed to effect contact with the contact pieces or prongs 18 in the sockets 16. Either lead 4 or 5 extends to the plug 24, lead 5 being shown as so extended in Figure 1, and the lead is divided to form terminals 5, 5, one engaging the usual contact binding screw 26 of one of the prongs 2 5, and the other engaging the corresponding binding screw of the other prong 25. Thus,

The spacing of the apertures 22 when the plug 24 has its prongs 25 in electrical contact with contact pieces 18, the circuit 45 includes the electrodes 17 and the fuse 20. As clearly seen in Figures 1, 2, and 3, I prefer to employ the new standard the plug 24, said fitting providing a right angle turn for the armored 28 of those parts of lead 5 which extend to the plug 24. Thus, when the present improved safety control apparatus is applied, a neat and workmanlike appearance will be afforded the finished connection and may be pro duced with ease and facility. However,

because the armor cable 28, which contains the branches of the lead 5,is usually pendent and might he accidentally or otherwise caused to be stressed away from the part 14, I provide a special anchorage. to preclude the possibility of accidental detachment of plug 24 from engagement in the sockets 16. To this end, each prong 25 is provided with a notch 29, onenotch 29 being at one edge of a prong 25, and the other notch being at the relatively opposite edge thereof, as indicated by the full line and dotted line positions in Figure 5. Cooperating with this notch, a set screw 30 is threaded throughthe socket head or cylindrical portion 14' preferably on an incline and in planes at rightangles to the planes of the flat faces of the prongs 25. The screw 30 is located to engage one ofthe notches 29. and to thereby effectively lock the engaged prong against withdrawal. Of course, the plug 24 and parts carried thereby are also locked by the locking of the engaged prong. The location and inclination of the screw 30 is such that as it contacts withone of the prongs 25 the further advance of the screw will tend to move the prong into more intimate contact with the respective contact piece 18. Also, it will be observed, as clearly seen in Figure 5, that each notch 29 is beveled to taper toward the inner or free end of the respective prong 25, so that any stress or pull exerted on the plug 24 tending to withdraw the same tends also to draw the surface of the respective notch 29 closer to the screw 30 and reactively tends to increase the contact between the respective prong 25 and the corresponding contact piece 18. Thus, not only are the parts effectively held against accidental dislodgment, but assurance is given that if a stress tending to dislodge occurs, any variation in contact caused thereby will be an improvement. It will be observed also that the location of the notches 29 at the respectively opposite edges of prongs 25 enables the user to insert the prongs 25 without special observation and with assurance that one of the notches will properly register with the screw 30. Y r

In operation, the shell 7 is located at that commercial fitting 27 as the connection with Cir elevation in the boiler predetermined by the conditions to be governed, and the parts continue to function so long as the temperature of the boiler does not rise to the danger pointor the liquid level in the boiler drop to the danger point. \Vhen either occurs, the increased temperature causes fus ing of the fuse element 20, which drops from the contactpieces 19, the central enlarged portion of the block being drawn by gravity in advance of the thinner portions and pulling all parts clear of the contact pieces 19. As shown as this has been accomplished, the circuit is broken, the motor 3 ceases functioning, and the supply of fuel is thus discontinued. Drop in temperature or pressure supplied from the boiler will indicate the action stated, and the operator will first repair or attend to whatever defect caused the dangerous condition, as, for instance, if the liquid level has dropped too low, he will refill the boiler. Next he will sufficiently back Oil screw 30 to release the plug 24, and will then pull the plug clear of the socket head 14. Next the operator will unscrew the threads 11 from the head 10 and withdraw the insulating bar 13 from shell 7. The presence of the shell 7, of course, insures preservation against leakage by the boiler even though the boiler be filled with water. The operator then withdraws the cap 23, clears out the residue of fused metal therein, withdraws wedging block 21, replaces a new fuse between the contact pieces 19, reapplies the wedging block 21, and then applies the cleaned cap 23, so that the parts are restored to their normal condition of assemblage. Then the insulating bar 13 is inserted into the shell 7, and the threads 11 are screwed home. The operator then inserts the prongs into the sockets 1G and clamps the parts in the locked-together condition by screwing down the screw to the position shown in Figure 3.

It should be understood that cap 23 is small enough to avoid contact or friction with the shell or tube 7, but is amply large to provide effective clearance for the molten mass of a fused fuse block, and, to provide additional space for accommodation of such molten material when found desirable, the insulating bar or rod 13 may be reduced at its inner extremity to provide an annular space or rabbet 31. Obviously, it is desirable to have the space 31 extend all about the rod 13 so as to assure provision of a space below the fuse block even though the threading of the rod 13 may not cause the lock to reach that idealistic final location indicated in Figure 4. Also, it is desirable to provide a second and much thinner rabbet in the bar 13 outward of rabbct 31 terminating in a shoulder 32 against which the ap 23 may abut to enable quick application of the cap and an assured limitation thereof against being forced too far onto rod 13.

The claims herein presented are restricted to specific details for the purpose of distinguishing them from the invention disclosed and claimed in applicants co-pending application Serial No. 363,623, wherein the generic claims are presented.

lVhat is claimed is 1. The combination with spaced electrical leads, of a fuse block interposed therebetween, and means additional to the fuse for clamping said leads against said block.

2. The combination with spaced electrical leads, of a fuse interposed therebetween, and means additional to the fuse for clamping said leads against said fuse and for wedging said leads into close electrical contact with said fuse.

3. The combination, with electrical leads, of a fuse located therebctween and in contact therewith, of an insulating block having means of engagement with said leads, said means of engagement being spaced apart a slightly less distance than the effective length of the fuse for causing the leads to be wedged toward each other when the insulating block is moved along the leads toward the fuse.

4. The combination, with electrical leads, of a fuse located therebetwcen and in contact therewith, and an insulating block having apertures proportioned to snugly receive said leads, said apertures being spaced. apart a less distance than the effective length of the fuse, and the insulating block being adapted to be forced along the leads toward the fuse for causing the leads to increase their contact with the fuse.

The combination of an insulating bar, electrical leads extending therethrough and projecting from one end of the bar, a fuse interposed between and electrically connecting the extended portions of said leads, and a cap removably mounted on the end of said bar from which said leads extend, said cap enclosing said fuse.

6. The combination of an insulating bar, electrical leads extending therethrough and projecting from one end of the bar, a fuse, interposed between and electrically connecting the extended portions of said leads, and a cap removably mounted on the end of said bar from which said leads extend, said cap enclosing said fuse, and said, in sulating bar being reduced within said cap for providing a receiving space for fused material of said fuse.

7. In apparatus of the class described, the combination of a metal housing adapted to be detachably extended into a boiler, an insulating rod detachably inserted in said housing, spaced electrical leads carried by said rod and extending into said housing, a. heat responsive fuse within said housing connecting said electrical leads, and insulating means interposed between the housing and said fuse.

8. In apparatus of the class described, the combination of a metal housing ada ted to be detachably extended into a boi er, an insulating rod detachably inserted in said housing, spaced electrical leads carried by said rod and extending into said housing, each of said leads terminating at its outer 1. portion in a contact pron within the insulating rod the insulating rod having socket openings for enabling the introduction of the prongs of an electric circuit plug into electrical contact with the prongs of said leads, a heat-responsive fuse connecting said leads within said housing, and means carried by said insulating rod for locking the plug prongs against withdrawal from said socket openings. In testimony whereof I afiix my signature.

FREDERICK D. AUSTIN. 

